In July 2005 Cassini completed a spectacularly close flyby of Enceladus, passing just 173km above its surface.
From this flyby came confirmation that the moon has an atmosphere, and strong evidence that the gases which make up the atmosphere are coming from cracks in the surface, nick-named "tiger stripes", near the south pole.
This false-colour image shows the extent of the active region (Image: Nasa/JPL/SSI)
It appears that the gases are being forced through the surface, as they emerge in jets which shoot upwards for hundreds of kilometres before dispersing, eventually forming Saturn's E-ring.
Most of the gas is water vapour, suggesting strongly that liquid water lies under the moon's icy surface.
From his base at the University of Arizona, Tucson, Bob Brown leads the scientific team for Cassini's visual and infrared mapping spectrometer (Vims) which analysed the chemical composition of Enceladus's atmosphere and mapped the distribution of various gases.
"We very clearly saw water; there's water everywhere on Enceladus, it's 99.9% water ice in general at the surface, and we've known that for years, so it wasn't a big surprise," he told the BBC News website.
"But when we started looking at our spectra we saw absorption bands from a compound that had to have carbon and hydrogen bonded together.
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